Time piece hairspring end fastening means

ABSTRACT

1,121,204. Springs. FABRIQUE D&#39;HORLOGERIE CHS TISSOT ET FILS S.A. 21 Sept., 1966 [24 Sept., 1965], No. 42189/66. Heading F2S. [Also in Division G3] The free outer end of a timepiece hairspring 2 is secured by bending it to conform with the surfaces of bosses 8-11. The bosses and a holder 3 are integrally moulded from plastics material, a hole 16 in the holder removing part of the boss 11 to define a lip 12. The outer turn of the hairspring 2 passes between a pin 13 and a key 14 of a regulator 6 and is then clamped between the bosses 9-11, the lip 12 and the key 14 supporting the spring in an axial direction.

1968 JEAN-CLAUDE SCHNEIDER 3,395,532

TIME PIECE HAIRSPRING END FASTENING MEANS Filed Sept. 12, 1966 United States Patent 01 fice 3,395,532 Patented Aug. 6, 1968 3,395,532 TIME PIECE HAIRSPRING END FASTENING MEANS Jean-Claude Schneider, Neuchatel, Switzerland, assignor to Fabrique dHorlogerie Chs. Tissot et Fils S.A., Le Locle, Neuchatel, Switzerland, a limited company of Switzerland Filed Sept. 12, 1966, Ser. No. 578,851 Claims priority, application Switzerland, Sept. 24, 1965, 13,244/ 65 10 Claims. (Cl. 58-115) The present invention relates to a means for fastening the outer end portion of a time piece hairspring.

In time piece movements, a hairspring is a fine blade spring element wound in the form of a flat ribbon or uniplanar coil around the axis of the balance wheel of the movement, the inner end of the coiled blade being attached to an element on the balance wheel axis and the outer blade end being attached to a rigid member, for example, a part of the stud holder.

Heretofore, the attachment of the outer end of the hairspring to the rigid member has presented various problems occasioned by the delicate nature of the spring and by the fact that known attachment means have tended to exert axial forces against the spring outer end whereby the outer turn or turns of the spring were axially displaced out of the plane of the inner turns so that the spring lost its fiat ribbon character. Further, known in attachment means, it has been a relatively difficult and delicate task to remove or replace a hairspring, such operation often resulting in a distortion or buckling of said spring occasioned by the fact that the spring end portion has to be threaded or snaked longitudinally through an opening means therefor.

It is, therefore, an object of this invention to provide an attachment means for the outer end of a hairspring, whereby the attachment of said outer end may be effected easily, effectively, and without disturbing the flatness of the spring ribbon.

It is a further object to provide an attachment means for a hairspring wherein said means effectively grips the spring end portion without exerting any forces on said spring in a direction parallel to the axis thereof, since such forces would tend to disrupt the flat, uni-planar disposition of all the spring turns.

It is a further object to provide such an attachment means through an arrangement which is itself simple and economical to construct.

These and other objects of the invention will be evident from the following detailed description of various preferred embodiments, which description is referred to the attached drawing, wherein:

FIGURE lis a plan view of a first embodiment;

FIGURE 2 is a plan view of a second embodiment;

FIGURE 3 is a partial sectional view taken along the line III-III of FIGURE 1;

FIGURE 4 is a partial sectional view along the line IVIV of FIGURE 1;

FIGURES 5 and 6 are sectional views corresponding to FIGURES 3 and 4 but showing a modification relative thereto; and,

FIGURE 7 is a sectional view corresponding to FIG- URES 4 and 6 but showing a modification relative thereto.

In FIGURES l and 2, a portion of a watch movement is shown wherein a bridge 5 serves as a support for stud holder 3 and regulator 6. Bridge 5 includes an opening 4 through which passes the balance wheel shaft 1. In both embodiments, FIGURES 1 and 2, the stud holder 3 includes a laterally extending arm 7, 7' upon which are mounted the respective attachment elements for the hairspring outer end portion.

In the embodiment of FIGURE 1, four cylindrical bosses 8, 9, 10, and 11 rigidly extend axially, or perpendicularly, from the flat surface 15 of arm 7, said fiat surface 15 being perpendicular to the axis of shaft 1. Further, the axes of bosses 8 to 11 are substantially aligned on a straight line, however, the outer surfaces of said bosses define bearing surfaces for spring 2 along a sinusoidal path. As is evident from FIGURES 3 and 4, the respective bosses 8 to 11 are integral or rigid with arm 7.

The outer turn of hairspring 2 first passes between pin 13 and key 14 of the regulator 6 and is then curved to pass along the inner axial face of bosses 8 and 9, the spring being bent outwardly along the face of boss 9 and around the outer face of boss 10 whereupon it continues from boss 10 to the inner face of boss 11. It will, therefore, be seen that since spring 2 is flexed along a sinusoidal path over the surfaces of the bosses, said bosses 9, 10, and 11 exert substantially opposed inward and outward radial (relative to the axis of shaft 1) forces against the end portion of spring 2, bosses 9 and 11 exerting substantially radially inward forces while intermediate boss 10 exerts a radially outward force. Boss 8 serves as a guide for curving the spring as it emerges from between elements 13 and 14 towards the inner face of boss 9. Elements 13 and 14 on regulator 6 serve to determine the effective length of the hairspring 2. It should be understood that the spring bears elastically against the respective axial (cylindrical) surfaces of bosses 8 to 11 so that it is continually flexed between the respective b osses. It should be noted, however, that the flexing forces are all in a radial direction, that is, perpendicular to the axis about Which spring 2 is Wound in the form of a flat ribbon. This orientation of the flexing forces provides a very effective attachment means for the spring end portion since the oppositely directed flexing forces provided by bosses 9, 10 and 11 constitute a clamping means between which the spring end portion is gripped. The flexing or clamping forces, however, do not include any component in an axial direction, so that the end portion of spring 2 is effectively attached to the arm 7 without any ltendency for the respective turns in said spring to move into different planes.

In the embodiment of FIGURE 1, the stud holder 3 is a one-piece injection-molded plastic material member, which, as is seen in FIGURE 4, includes a lip 12 radially extending from the axial surface of boss 11. This lip is conveniently formed by providing a cylindrical core member in the injection mold in which the stud holder is molded, said core member producing a cylindrical opening 16 in arm 7, which opening overlaps the circumference of boss 11 and thereby results in a boss 11 which includes an inwardly concave notch portion 11'. The core in the mold, however, does not extend the full axial length of boss 11 so that the free end of boss 11 retains its full circle configuration and that portion of the circle which is axially adjacent notch 11 constitutes lip 12. Spring 2 rests axially against lip 12 (FIGURE 4) so that lip 12 and regulator 6 both form an axial support or guide means for the end portion of spring 2. In other words, lip 12 and key 14 restrain the spring end portion against any tendency for it to slip in an axial direction along the boss surfaces towards the free ends of said boss members.

In FIGURE 2, the stud holder arm 22 (corresponding to arm 7) includes three (instead of four) bosses 23, 24, 25 extending perpendicularly from flat face 30. The first boss 23 is elongated rather than circular in cross section and has a flat external or outer radial face. The side or axial face of boss 23 defines a series of curvilinear and flat generatrices perpendicular to said face 30. Second boss 24 of circular form is located opposite to the end of a flat portion of the axial face of boss 23 and is spaced 3 therefrom a distance equal to the thickness of blade spring 27 (corresponding to spring 2).

In the embodiment of FIGURE 2, the regulator 6 includes a single cylindrical pin 29 instead of the pin 13 and key 14 of FIGURE 1. The end portion of spring 27, therefore, bears against the inner axial side of pin 29 (which serves in this instance as a guide boss analogous to boss 8 in FIGURE 1) and is then curved to pass against the inner curved side of boss 23 where spring 27 is bent at 31 to extend between bosses 23 and 24. Spring 27 is then bent at 32 against the boss 24 and then bears against the inner side of cylindrical boss 25. Boss 25 and hole 26 are analogous to boss 11 and hole 16 in FIGURE 1 so that boss 25 also includes a lip analogous to lip 12.

The three bosses 23, 24, and 25, therefore, determine a sinusoidal path for spring 27 whereby said spring is radially flexed in opposite directions between bosses 23 and 25 on one side and boss 24 on the other.

FIGURES and 6 illustrate the details of a stud holder which is metallic instead of being of plastic material. In FIGURES 5 and 6, the stud holder arm 17 (corresponding to either arm 7 or 30) is a metal plate and bosses 19 and 20 (corresponding to either bosses 10 and 11 or 24 and 25) are integrally formed in a plastic base 18 which in turn is attached to metal plate 17 by means of protrusion 21 which is force-fitted into an opening in said metal plate.

FIGURE 7 illustrates a variation over FIGURES 4 and 6 in the lip means 12. Instead of providing a radial protrusion such as lip 12, in FIGURE 7 the inner axial face of the last boss (corresponding the bosses 11 and 25 is outwardly inclined at 33 thereby forming an inclined ledge. Spring 2 or 27 will, therefore, be elastically wedged between said inclined face 33 and the fiat face 34 of the stud holder arm (7 or The aforedescribed embodiments and modifications thereto provide a hairspring attachment means which assures that the spring will not be subjected to either torsional or buckling forces. No forces act upon the spring in an axial direction, that is, in a direction parallel to the spring axis. The only forces acting upon the spring are perpendicular to the spring axis and these forces do not tend to disturb the fiat, uni-planar disposition of the spring turns.

The fact that the respective bosses are all free at one end thereof makes it possible to interlace the spring between the respective bosses simply by sliding the spring blade edgewise, or in an axial direction between the respective bosses. In other words, if the bosses were not free at one end thereof, it would be necessary to snake the spring along the boss surfaces, this being relatively difficult, and dangerous in that the spring is subjected to buckling and deforming stresses in such a snaking operation.

Although in the embodiments described the spring is located below the disc of the balance wheel, the boss arrangement described can also be used in a watch piece in which the spring extends above the balance wheel. In such a case, the boss support and the bosses can be made integral with the cock. They can also be mounted on a movable stud holder which pivots around the cock end piece and is located above or below the regulator.

The herein presented embodiments and the details thereof are intended only for illustrative purposes and are not intended to be limitative of the scope of the claims presented herein, said scope being applicable to all obvious modifications and/ or equivalents to which the basic inventive concept is susceptible.

What is claimed is:

1. In a time piece movement comprising a hairspring wound in the form of a ribbon about an axis, an attachment means securing the free outer end of said spring, said means comprising: a plurality of bearing surfaces extending parallel to said axis, said surfaces being arranged so as to define a substantially sinusoidal path, said spring outer end extending along said path with said spring outer end being flexibly bent in conformity with said surfaces.

2. The movement of claim 1. said means comprising at least three of said surfaces, one of said surfaces being disposed on one axial side of said spring and the other two being disposed on the other side of said spring.

3. The movement of claim 2, said movement including a stud holder and said surfaces being rigidly located on said stud holder.

4. The movement of claim. 3, including a regulator having a key and pin for determining the effective length of said hairspring, said means including a fourth said surface disposed on said stud holder on the same side of said spring as said other two surfaces, said spring outer end passing between the regulator key and pin and then along said fourth surface and a first one of said other two surfaces, said spring outer end then passing along said one surface and finally along the second of said other two surfaces.

5. The movement of claim 3, including a regulator having a cylindrical pin for determining the effective length of said hairspring, said spring outer end bearing against said pin and then passing directly to the first of said other two surfaces, said spring outer end then passing along said one surface and finally along the second of said two other surfaces.

6. The movement of claim 2, said surfaces being the outer axial surfaces of boss members rigidly supported in a fiat radial face, said flat face being perpendicular to the axis of said spring.

7. The movement of claim 6, said boss members having free ends opposite to said fiat face, said spring outer end being movable axially along said surfaces in the direction away from said fiat face.

8. The movement of claim 7, including a lip radially overlapping one of said surfaces at the free end of one of said boss members.

9. The movement of claim 6, including a metal base member, a molded plastic member attached to said base member, said plastic member comprising at least one of References Cited UNITED STATES PATENTS 498,209 5/1893 Duncan 58-1 15 772,106 11/1904 Lange 58-115 3,046,725 7/ 1962 Vuilleumier 581 15 FOREIGN PATENTS 1,145,347 5/1957 France.

261,671 9/ 1949 Switzerland.

ROBERT S. WARD, JR., Primary Examiner. S. A. WAL, Assistant Examiner. 

1. IN A TIME PIECE MOVEMENT COMPRISING A HAIRSPRING WOUND IN THE FORM OF A RIBBON ABOUT AN AXIS, AN ATTACHMENT MEANS SECURING THE FREE OUTER END OF SAID SPRING, SAID MEANS COMPRISING: A PLURALITY OF BEARING SURFACES EXTENDING PARALLEL TO SAID AXIS, SAID SURFACES BEING ARRANGED SO AS TO DEFINE A SUBSTANTIALLY SINUSOIDAL PATH, SAID SPRING OUTER END EXTENDING ALONG SAID PATH WITH SAID SPRING OUTER END BEING FLEXIBLY BENT IN CONFORMITY WITH SAID SURFACES. 